At this stage, one may observe that the BenDaniel-Duke form [1]} of the kinetic energy operator adopted in (REF ) is only a special case of the von Roos general two-parameter form [2]}. Other orderings of the mass and the differential operator, such as the Zhu-Kroemer [3]} or the Mustafa-Mazharimousavi [4]}, [5]} ones, which pass the de Souza Dutra and Almeida test [6]}, might have been chosen, but, as shown elsewhere [7]}, in general they do not change the results much.
